During a traffic stop, can a police officer search your car without a warrant?

Under the Fourth Amendment, you are protected against unreasonable searches and seizures. During a traffic stop, an officer generally needs a warrant to search your vehicle, but the Supreme Court has recognized several exceptions. The automobile exception allows a warrantless search if the officer has probable cause to believe the car contains evidence of a crime. If you consent to the search, the search is lawful regardless of whether evidence is found. You have the right to clearly and calmly state 'I do not consent to a search,' though you cannot physically resist. Refusing consent does not give the officer automatic grounds for a search.